LightEnv.h

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/* Copyright (C) 2012 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * CLightEnv, a class describing the current lights
 */

#ifndef INCLUDED_LIGHTENV
#define INCLUDED_LIGHTENV

#include "graphics/Color.h"
#include "maths/MathUtil.h"
#include "maths/Vector3D.h"

class CMapWriter;
class CMapReader;

/**
 * Class CLightEnv: description of a lighting environment - contains all the
 * necessary parameters for representation of the lighting within a scenario
 */
class CLightEnv
{
friend class CMapWriter;
friend class CMapReader;
friend class CXMLReader;
private:
    /**
     * Height of sun above the horizon, in radians.
     * For example, an elevation of M_PI/2 means the sun is straight up.
     */
    float m_Elevation;

    /**
     * Direction of sun on the compass, in radians.
     * For example, a rotation of zero means the sun is in the direction (0,0,-1)
     * and a rotation of M_PI/2 means the sun is in the direction (1,0,0) (not taking
     * elevation into account).
     */
    float m_Rotation;

    /**
     * Vector corresponding to m_Elevation and m_Rotation.
     * Updated by CalculateSunDirection.
     */
    CVector3D m_SunDir;

    /**
     * A string that shaders use to determine what lighting model to implement.
     * Current recognised values are "old" and "standard".
     */
    std::string m_LightingModel;

public:
    RGBColor m_SunColor;
    RGBColor m_TerrainAmbientColor;
    RGBColor m_UnitsAmbientColor;
    RGBColor m_FogColor;

    float m_FogFactor;
    float m_FogMax;
    
    float m_Brightness, m_Contrast, m_Saturation, m_Bloom;

public:
    CLightEnv();

    float GetElevation() const { return m_Elevation; }
    float GetRotation() const { return m_Rotation; }
    const CVector3D& GetSunDir() const { return m_SunDir; }
    const std::string& GetLightingModel() const { return m_LightingModel; }

    void SetElevation(float f);
    void SetRotation(float f);

    void SetLightingModel(const std::string& model) { m_LightingModel = model; }

    /**
     * Calculate brightness of a point of a unit with the given normal vector,
     * for rendering with CPU lighting.
     * The resulting color contains both ambient and diffuse light.
     * To cope with sun overbrightness, the color is scaled by 0.5.
     *
     * @param normal normal vector (must have length 1)
     */
    RGBColor EvaluateUnitScaled(const CVector3D& normal) const
    {
        float dot = -normal.Dot(m_SunDir);

        RGBColor color = m_UnitsAmbientColor;
        if (dot > 0)
            color += m_SunColor * dot;

        return color * 0.5f;
    }

    /**
     * Compute the diffuse sun lighting color on terrain, for rendering with CPU lighting.
     * To cope with sun overbrightness, the color is scaled by 0.5.
     *
     * @param normal normal vector (must have length 1)
     */
    SColor4ub EvaluateTerrainDiffuseScaled(const CVector3D& normal) const
    {
        float dot = -normal.Dot(m_SunDir);
        return ConvertRGBColorTo4ub(m_SunColor * dot * 0.5f);
    }

    /**
     * Compute the diffuse sun lighting factor on terrain, for rendering with shader lighting.
     *
     * @param normal normal vector (must have length 1)
     */
    SColor4ub EvaluateTerrainDiffuseFactor(const CVector3D& normal) const
    {
        float dot = -normal.Dot(m_SunDir);
        int c = clamp((int)(dot * 255), 0, 255);
        return SColor4ub(c, c, c, 255);
    }

    // Comparison operators
    bool operator==(const CLightEnv& o) const
    {
        return m_Elevation == o.m_Elevation &&
            m_Rotation == o.m_Rotation &&
            m_LightingModel == o.m_LightingModel &&
            m_SunColor == o.m_SunColor &&
            m_TerrainAmbientColor == o.m_TerrainAmbientColor &&
            m_UnitsAmbientColor == o.m_UnitsAmbientColor &&
            m_FogColor == o.m_FogColor &&
            m_FogFactor == o.m_FogFactor &&
            m_FogMax == o.m_FogMax &&
            m_Brightness == o.m_Brightness &&
            m_Contrast == o.m_Contrast &&
            m_Saturation == o.m_Saturation &&
            m_Bloom == o.m_Bloom;
    }

    bool operator!=(const CLightEnv& o) const
    {
        return !(*this == o);
    }

private:
    void CalculateSunDirection();
};

#endif // INCLUDED_LIGHTENV